Part 3. Designing and building GraphQL APIs

In part 2, you learned that REST is an API technology that allows us to alter or retrieve the state of a resource from the server. When a resource is represented by a large payload, fetching it from the server translates to a large amount of data transfer. With the emergence of API clients running in mobile devices with restricted network access and limited storage and memory capacity, exchanging large payloads often results in unreliable communication. In 2012, Facebook was acutely aware of these problems, and it developed a new technology to allow API clients to run granular data queries on the server. This technology was released in 2015 under the name of GraphQL.

GraphQL is a query language for APIs. Instead of fetching full representations of resources, GraphQL allows you to fetch one or more properties of a resource, such as the price of a product or the status of an order. With GraphQL, we can also model the relationship between different objects, which allows us to retrieve, in a single request, the properties of various resources from the server, such as a product’s ingredients and its stock availability.

Despite its benefits, many developers aren’t familiar with GraphQL or don’t know how it works, and therefore it isn’t usually the first choice of technology for building an API. In part 3, you learn everything you need to know to design and build high-quality GraphQL APIs and how to consume them. After reading part 3, you’ll know what GraphQL is, how it works, and when to use it so that you can make better decisions in your API strategy.